Pickup trucks may be used to transport various types of cargo. These trucks generally have a flat bed or floor near the rear of the vehicle, into which the cargo can be loaded. A rear door or tailgate provides access to the bed and may be opened and closed for loading. In the closed or raised condition, the tailgate keeps cargo from rolling or falling out of the bed. The trucks may be designed so that, when the tailgate is folded down for cargo loading, an interior surface of the tailgate is level with the bed floor.
Certain types of cargo may occupy more floor space than may be available in a standard cargo bed. For such situations, certain devices have been designed to allow a lowered tailgate to serve as an extension of the bed. These devices allow loaded cargo to extend past the end of the standard bed and to occupy a portion of the folded-down tailgate interior surface when the tailgate is down, while preventing the cargo from falling out of the bed. However, when the cargo bed is extended, a bed cover (such as a tonneau cover) structured to cover the normal-sized bed will generally not be able to cover the extended portion of the bed.